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Is Tree Species Diversity or Species Identity the More Important Driver of Soil Carbon Stocks, C/N Ratio, and pH?

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Abstract

We explored tree species diversity effects on soil C stock, C/N ratio, and pH as compared with effects of tree species identity. We sampled forest floors and mineral soil (0–40 cm) in a diversity gradient of 1–5 tree species composed of conifers and broadleaves in Białowieża Forest, Poland. Diversity was a weaker driver than identity of soil C stocks, C/N ratio, and pH in the soil profile. However, there were significant non-additive effects of diversity and significant effects of identity on C stock and C/N ratio within different parts of the soil profile. More diverse forests had higher C stocks and C/N ratios in the 20–40 cm layer, whereas identity in terms of conifer proportion increased C stocks and C/N ratios only in forest floors. A positive relationship between C stocks and root biomass in the 30–40 cm layer suggested that belowground niche complementarity could be a driving mechanism for higher root carbon input and in turn a deeper distribution of C in diverse forests. Diversity and identity affected soil pH in topsoil with positive and negative impacts, respectively. More diverse forests would lead to higher soil nutrient status as reflected by higher topsoil pH, but there was a slight negative effect on N status as indicated by higher C/N ratios in the deeper layers. We conclude that tree species diversity increases soil C stocks and nutrient status to some extent, but tree species identity is a stronger driver of the studied soil properties, particularly in the topsoil.

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References

  • Augusto L, De Schrijver A, Vesterdal L, Smolander A, Prescott C, Ranger J. 2015. Influences of evergreen gymnosperm and deciduous angiosperm tree species on the functioning of temperate and boreal forests. Biol Rev 90:444–66.

    Article  PubMed  Google Scholar 

  • Baeten L, Verheyen K, Wirth C, Bruelheide H, Bussotti F, Finér L, Jaroszewicz B, Selvi F, Valladares F, Allan E, Ampoorter E, Auge H, Avăcăriei D, Barbaro L, Bărnoaiea I, Bastias CC, Bauhus J, Beinhoff C, Benavides R, Benneter A, Berger S, Berthold F, Boberg J, Bonal D, Brüggemann W, Carnol M, Castagneyrol B, Charbonnier Y, Chećko E, Coomes D, Coppi A, Dalmaris E, Dănilă G, Dawud SM, de Vries W, De Wandeler H, Deconchat M, Domisch T, Duduman G, Fischer M, Fotelli M, Gessler A, Gimeno TE, Granier A, Grossiord C, Guyot V, Hantsch L, Hättenschwiler S, Hector A, Hermy M, Holland V, Jactel H, Joly F-X, Jucker T, Kolb S, Koricheva J, Lexer MJ, Liebergesell M, Milligan H, Müller S, Muys B, Nguyen D, Nichiforel L, Pollastrini M, Proulx R, Rabasa S, Radoglou K, Ratcliffe S, Raulund-Rasmussen K, Seiferling I, Stenlid J, Vesterdal L, von Wilpert K, Zavala MA, Zielinski D, Scherer-Lorenzen M. 2013. A novel comparative research platform designed to determine the functional significance of tree species diversity in European forests. Perspect Plant Ecol Evol Syst 15:281–91.

    Article  Google Scholar 

  • Ball BA, Carrillo Y, Molina M. 2014. The influence of litter composition across the litter–soil interface on mass loss, nitrogen dynamics and the decomposer community. Soil Biol Biochem 69:71–82.

    Article  CAS  Google Scholar 

  • Bardgett RD, Bowman WD, Kaufmann R, Schmidt SK. 2005. A temporal approach to linking aboveground and belowground ecology. Trends Ecol Evol 20:634–41.

    Article  PubMed  Google Scholar 

  • Bates DM. 2010. lme4: mixed-effects modeling with R. New York: Springer.

    Google Scholar 

  • Brassard BW, Chen HYH, Bergeron Y, Paré D. 2011. Differences in fine root productivity between mixed- and single-species stands. Funct Ecol 25:238–46.

    Article  Google Scholar 

  • Brassard BW, Chen HYH, Cavard X, Laganière J, Reich PB, Bergeron Y, Paré D, Yuan Z, Chen H. 2013. Tree species diversity increases fine root productivity through increased soil volume filling. J Ecol 101:210–19.

    Article  Google Scholar 

  • Breheny P, Burchett W. 2013. Visualization of Regression Models Using visreg.

  • Brussaard L. 1997. Biodiversity and ecosystem functioning in soil. Ambio 26:563–70.

    Google Scholar 

  • Cesarz S, Ruess L, Jacob M, Jacob A, Schaefer M, Scheu S. 2013. Tree species diversity versus tree species identity: driving forces in structuring forest food webs as indicated by soil nematodes. Soil Biol Biochem 62:36–45.

    Article  CAS  Google Scholar 

  • Chatterjee S, Hadi AS. 2006. Regression analysis by example. Hoboken: Wiley.

    Book  Google Scholar 

  • Cools N, Vesterdal L, De Vos B, Vanguelova E, Hansen K. 2014. Tree species is the major factor explaining C:N ratios in European forest soils. Forest Ecol Manag 311:3–16.

    Article  Google Scholar 

  • Cotrufo MF, Wallenstein MD, Boot CM, Denef K, Paul E. 2013. The microbial efficiency-matrix stabilization (MEMS) framework integrates plant litter decomposition with soil organic matter stabilization: do labile plant inputs form stable soil organic matter? Glob Chang Biol 19:988–95.

    Article  PubMed  Google Scholar 

  • Crawley MJ. 2012. Analysis of variance. The R book. Chichester: Wiley. pp 498–536.

    Google Scholar 

  • de Schrijver A, de Frenne P, Staelens J, Verstraeten G, Muys B, Vesterdal L, Wuyts K, van Nevel L, Schelfhout S, de Neve S, Verheyen K. 2012. Tree species traits cause divergence in soil acidification during four decades of postagricultural forest development. Glob Chang Biol 18:1127–40.

    Article  Google Scholar 

  • Faliński JB. 1986. Vegetation dynamics at temperate lowland primeval forest: Ecological studies in Bialowieza forest. Dordrecht: Dr. W. Junk Publishers.

    Book  Google Scholar 

  • Forrester DI. 2014. The spatial and temporal dynamics of species interactions in mixed-species forests: from pattern to process. Forest Ecol Manag 312:282–92.

    Article  Google Scholar 

  • Forrester DI, Kohnle U, Albrecht AT, Bauhus J. 2013a. Complementarity in mixed-species stands of Abies alba and Picea abies varies with climate, site quality and stand density. Forest Ecol Manag 304:233–42.

    Article  Google Scholar 

  • Forrester DI, Pares A, O’Hara C, Khanna PK, Bauhus J. 2013b. Soil organic carbon is increased in mixed-species plantations of eucalyptus and nitrogen-fixing acacia. Ecosystems 16:123–32.

    Article  CAS  Google Scholar 

  • Frouz J, Livečková M, Albrechtová J, Chroňáková A, Cajthaml T, Pižl V, Háněl L, Starý J, Baldrian P, Lhotáková Z, Šimáčková H, Cepáková Š. 2013. Is the effect of trees on soil properties mediated by soil fauna? A case study from post-mining sites. Forest Ecol Manag 309:87–95.

    Article  Google Scholar 

  • Gamfeldt L, Snall T, Bagchi R, Jonsson M, Gustafsson L, Kjellander P, Ruiz-Jaen MC, Froberg M, Stendahl J, Philipson CD, Mikusinski G, Andersson E, Westerlund B, Andren H, Moberg F, Moen J, Bengtsson J. 2013. Higher levels of multiple ecosystem services are found in forests with more tree species. Nat Commun 4:1340.

    Article  PubMed  PubMed Central  Google Scholar 

  • Göransson H, Wallander H, Ingerslev M, Rosengren U. 2006. Estimating the relative nutrient uptake from different soil depths in Quercus robur, Fagus sylvatica and Picea abies. Plant Soil 286:87–97.

    Article  Google Scholar 

  • Grapher™ 11 Golden Software LLC. Golden Software, LLC. 809 14th Street Golden, Colorado 80401 www.goldensoftware.com.

  • Grömping U. 2006. Relative importance for linear regression in R: the package relaimpo. J Stat Softw 17:1–27.

    Article  Google Scholar 

  • Guckland A, Jacob M, Flessa H, Thomas FM, Leuschner C. 2009. Acidity, nutrient stocks, and organic-matter content in soils of a temperate deciduous forest with different abundance of European beech (Fagus sylvatica L.). J Plant Nutr Soil Sci 172:500–11.

    Article  CAS  Google Scholar 

  • Hansen K, Vesterdal L, Schmidt IK, Gundersen P, Sevel L, Bastrup-Birk A, Pedersen LB, Bille-Hansen J. 2009. Litterfall and nutrient return in five tree species in a common garden experiment. Forest Ecol Manag 257:2133–44.

    Article  Google Scholar 

  • Hansson K, Fröberg M, Helmisaari H-S, Kleja DB, Olsson BA, Olsson M, Persson T. 2013. Carbon and nitrogen pools and fluxes above and below ground in spruce, pine and birch stands in southern Sweden. Forest Ecol Manag 309:28–35.

    Article  Google Scholar 

  • Hättenschwiler S, Gasser P. 2005. Soil animals alter plant litter diversity effects on decomposition. Proc Natl Acad Sci USA 102:1519–24.

    Article  PubMed  PubMed Central  Google Scholar 

  • Hector A, Bazeley-White E, Loreau M, Otway S, Schmid B. 2002. Overyielding in grassland communities: testing the sampling effect hypothesis with replicated biodiversity experiments. Ecol Lett 5:502–11.

    Article  Google Scholar 

  • Jandl R, Lindner M, Vesterdal L, Bauwens B, Baritz R, Hagedorn F, Johnson DW, Minkkinen K, Byrne KA. 2007. How strongly can forest management influence soil carbon sequestration? Geoderma 137:253–68.

    Article  CAS  Google Scholar 

  • Jastrow JD, Miller RM, Lussenhop J. 1998. Contributions of interacting biological mechanisms to soil aggregate stabilization in restored prairie1. Soil Biol Biochem 30:905–16.

    Article  CAS  Google Scholar 

  • Jost L. 2006. Entropy and diversity. Oikos 113:363–75.

    Article  Google Scholar 

  • Jucker T, Bouriaud O, Avacaritei D, Coomes DA. 2014. Stabilizing effects of diversity on aboveground wood production in forest ecosystems: linking patterns and processes. Ecol Lett 17:1560–9.

    Article  PubMed  Google Scholar 

  • Jucker T, Bouriaud O, Coomes DA. 2015. Crown plasticity enables trees to optimize canopy packing in mixed-species forests. Funct Ecol 29:1078–86.

    Article  Google Scholar 

  • Kooijman AM. 2010. Litter quality effects of beech and hornbeam on undergrowth species diversity in Luxembourg forests on limestone and decalcified marl. J Veg Sci 21:248–61.

    Article  Google Scholar 

  • Kuiters AT. 1990. Role of phenolic substances from decomposing forest litter in plant-soil interactions. Acta Bot Neerlandica 39:329–48.

    Article  CAS  Google Scholar 

  • Laclau J-P, Nouvellon Y, Reine C, Gonçalves Jd, Krushe A, Jourdan C, le Maire G, Bouillet J-P. 2013. Mixing Eucalyptus and Acacia trees leads to fine root over-yielding and vertical segregation between species. Oecologia 172:903–13.

    Article  PubMed  Google Scholar 

  • Lang C, Polle A. 2011. Ectomycorrhizal fungal diversity, tree diversity and root nutrient relations in a mixed Central European forest. Tree Physiol 31:531–8.

    Article  PubMed  Google Scholar 

  • Lange M, Eisenhauer N, Sierra CA, Bessler H, Engels C, Griffiths RI, Mellado-Vazquez PG, Malik AA, Roy J, Scheu S, Steinbeiss S, Thomson BC, Trumbore SE, Gleixner G. 2015. Plant diversity increases soil microbial activity and soil carbon storage. Nat Commun 6:6707.

    Article  CAS  PubMed  Google Scholar 

  • Lei P, Scherer-Lorenzen M, Bauhus J. 2012. The effect of tree species diversity on fine-root production in a young temperate forest. Oecologia 169:1105–15.

    Article  PubMed  Google Scholar 

  • Lindeman RH, Merenda PF, Gold RZ. 1980. Introduction to bivariate and multivariate analysis. Glenview IL: Scott, Foresman.

    Google Scholar 

  • Lindroos A-J, Derome J, Derome K, Smolander A. 2011. The effect of Scots pine, Norway spruce and silver birch on the chemical composition of stand throughfall and upper soil percolation water in northern Finland. Boreal Environ Res 16:240–50.

    CAS  Google Scholar 

  • Loreau M, Hector A. 2001. Partitioning selection and complementarity in biodiversity experiments. Nature 412:72–6.

    Article  CAS  PubMed  Google Scholar 

  • Matejovic I. 1993. Determination of carbon, hydrogen, and nitrogen in soils by automated elemental analysis (dry combustion method). Commun Soil Sci Plant Anal 24:2213–22.

    Article  CAS  Google Scholar 

  • Miles J. 1986. What are the effects of trees on soils? In: Jenkins D, Ed. Trees and wildlife in the Scottish uplands, NERC/ITE, 55-62. (ITE Symposium, 17). Scotland: CEH NORA, p. 55–62.

  • Mueller K, Eissenstat D, Hobbie S, Oleksyn J, Jagodzinski A, Reich P, Chadwick O, Chorover J. 2012. Tree species effects on coupled cycles of carbon, nitrogen, and acidity in mineral soils at a common garden experiment. Biogeochemistry 111:601–14.

    Article  CAS  Google Scholar 

  • Nadrowski K, Wirth C, Scherer-Lorenzen M. 2010. Is forest diversity driving ecosystem function and service? Curr Opin Environ Sustain 2:75–9.

    Article  Google Scholar 

  • Oelmann Y, Potvin C, Mark T, Werther L, Tapernon S, Wilcke W. 2010. Tree mixture effects on aboveground nutrient pools of trees in an experimental plantation in Panama. Plant Soil 326:199–212.

    Article  CAS  Google Scholar 

  • Paquette A, Messier C. 2011. The effect of biodiversity on tree productivity: from temperate to boreal forests. Glob Ecol Biogeogr 20:180.

    Article  Google Scholar 

  • Phillips RP, Brzostek E, Midgley MG. 2013. The mycorrhizal-associated nutrient economy: a new framework for predicting carbon–nutrient couplings in temperate forests. New Phytol 199:51.

    Article  Google Scholar 

  • Pinheiro JC, Bates DM. 2000. Mixed-effects models in S and S-PLUS. New York: Springer.

    Book  Google Scholar 

  • Prescott CE, Vesterdal L. 2013. Tree species effects on soils in temperate and boreal forests: emerging themes and research needs. Forest Ecol Manag 309:1–3.

    Article  Google Scholar 

  • R Core Team. 2014. R: a language and environment for statistical computing. Computing RFfS editor. Vienna: R Foundation for Statistical Computing.

  • Reich PB, Oleksyn J, Modrzynski J, Mrozinski P, Hobbie SE, Eissenstat DM, Chorover J, Chadwick OA, Hale CM, Tjoelker MG. 2005. Linking litter calcium, earthworms and soil properties: a common garden test with 14 tree species. Ecol Lett 8:811–18.

    Article  Google Scholar 

  • Rosengren U, Göransson H, Jönsson U, Stjernquist I, Thelin G, Wallander H. 2006. Functional biodiversity aspects on the nutrient sustainability in forests-importance of root distribution. J Sustain Forest 21:77–100.

    Article  Google Scholar 

  • Rothe A, Binkley D. 2001. Nutritional interactions in mixed species forests: a synthesis. Can J Forest Res 31:1855–70.

    Article  Google Scholar 

  • Rumpel C, Kögel-Knabner I. 2011. Deep soil organic matter—a key but poorly understood component of terrestrial C cycle. Plant Soil 338:143–58.

    Article  CAS  Google Scholar 

  • Saetre P, Brandtberg P-O, Lundkvist H, Bengtsson J. 1999. Soil organisms and carbon, nitrogen and phosphorus mineralisation in Norway spruce and mixed Norway spruce–Birch stands. Biol Fertil Soils 28:382–8.

    Article  Google Scholar 

  • Scheibe A, Steffens C, Seven J, Jacob A, Hertel D, Leuschner C, Gleixner G. 2015. Effects of tree identity dominate over tree diversity on the soil microbial community structure. Soil Biol Biochem 81:219–27.

    Article  CAS  Google Scholar 

  • Scherer-Lorenzen M, Luis Bonilla J, Potvin C. 2007a. Tree species richness affects litter production and decomposition rates in a tropical biodiversity experiment. Oikos 116:2108–24.

    Article  Google Scholar 

  • Scherer-Lorenzen M, Schulze E-D, Don A, Schumacher J, Weller E. 2007b. Exploring the functional significance of forest diversity: a new long-term experiment with temperate tree species (BIOTREE). Perspect Plant Ecol Evol Syst 9:53–70.

    Article  Google Scholar 

  • Schleuß P-M, Heitkamp F, Leuschner C, Fender A-C, Jungkunst HF. 2014. Higher subsoil carbon storage in species-rich than species-poor temperate forests. Environ Res Lett 9:014007.

    Article  Google Scholar 

  • Schmidt M, Veldkamp E, Corre MD. 2015. Tree species diversity effects on productivity, soil nutrient availability and nutrient response efficiency in a temperate deciduous forest. Forest Ecol Manag 338:114–23.

    Article  Google Scholar 

  • Schumacher BA. 2002. Methods for the determination of total organic carbon (TOC) in soils and sediments. Washington, DC: United States Environmental Protection Agency, office of Research and Development National Exposure Research Lab Environmental Sciences Division, p. 25.

  • Schwartz MW, Brigham CA, Hoeksema JD, Lyons KG, Mills MH, van Mantgem PJ. 2000. Linking biodiversity to ecosystem function: implications for conservation ecology. Oecologia 122:297–305.

    Article  Google Scholar 

  • Schwarz B, Dietrich C, Cesarz S, Scherer-Lorenzen M, Auge H, Schulz E, Eisenhauer N. 2015. Non-significant tree diversity but significant identity effects on earthworm communities in three tree diversity experiments. Eur J Soil Biol 67:17–26.

    Article  Google Scholar 

  • Shannon CE. 1948. A mathematical theory of communication. Bell Syst Tech J 27:379–423.

    Article  Google Scholar 

  • Skjemstad J, Baldock JA. 2007. Total and organic carbon. In: Carter MR, Gregorich EG, Eds. Soil sampling and methods of analysis. Boca Raton: Soil Science Society of Canada, CRC Press.

    Google Scholar 

  • Van Nevel L, Mertens J, De Schrijver A, Baeten L, De Neve S, Tack FMG, Meers E, Verheyen K. 2013. Forest floor leachate fluxes under six different tree species on a metal contaminated site. Sci Total Environ 447:99–107.

    Article  PubMed  Google Scholar 

  • Van Nevel L, Mertens J, Staelens J, De Schrijver A, Tack FMG, De Neve S, Meers E, Verheyen K. 2011. Elevated Cd and Zn uptake by aspen limits the phytostabilization potential compared to five other tree species. Ecol Eng 37:1072–80.

    Article  Google Scholar 

  • Vergutz L, Manzoni S, Porporato A, Novais RF, Jackson RB. 2012. Global resorption efficiencies and concentrations of carbon and nutrients in leaves of terrestrial plants. Ecol Monogr 82:205–20.

    Article  Google Scholar 

  • Vesterdal L, Clarke N, Sigurdsson BD, Gundersen P. 2013. Do tree species influence soil carbon stocks in temperate and boreal forests? Forest Ecol Manag 309:4–18.

    Article  Google Scholar 

  • Vesterdal L, Elberling B, Christiansen JR, Callesen I, Schmidt IK. 2012. Soil respiration and rates of soil carbon turnover differ among six common European tree species. Forest Ecol Manag 264:185–96.

    Article  Google Scholar 

  • Vesterdal L, Raulund-Rasmussen K. 1998. Forest floor chemistry under seven tree species along a soil fertility gradient. Can J Forest Res 28:1636–47.

    Article  CAS  Google Scholar 

  • Vesterdal L, Schmidt IK, Callesen I, Nilsson LO, Gundersen P. 2008. Carbon and nitrogen in forest floor and mineral soil under six common European tree species. Forest Ecol Manag 255:35–48.

    Article  Google Scholar 

  • Vila M, Vayreda J, Gracia C, Ibanez J. 2004. Biodiversity correlates with regional patterns of forest litter pools. Oecologia 139:641–6.

    Article  PubMed  Google Scholar 

  • Vogt K, Vogt D, Moore E, Sprugel D. 1989. Methodological considerations in measuring biomass, production, respiration and nutrient resorption for tree roots in natural ecosystems. In: Torrey J, Winship L, Eds. Applications of continuous and steady-state methods to root biology. Netherlands: Springer. p 217–32.

    Chapter  Google Scholar 

  • Wardle DA, Bonner KI, Nicholson KS. 1997. Biodiversity and plant litter: experimental evidence which does not support the view that enhanced species richness improves ecosystem function. Oikos 79:247–58.

    Article  Google Scholar 

  • Wardle DA, Yeates GW, Barker GM, Bonner KI. 2006. The influence of plant litter diversity on decomposer abundance and diversity. Soil Bio Biochem 38:1052–62.

    Article  CAS  Google Scholar 

  • Yang Y, Luo Y. 2011. Carbon: nitrogen stoichiometry in forest ecosystems during stand development. Glob Ecol Biogeogr 20:354–61.

    Article  Google Scholar 

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Acknowledgements

The FunDivEUROPE project received funding from the European Union’s Seventh Framework Program for research, technological development, and demonstration under Grant Agreement No. [265171]. We thank Dawid Zielinski, Izabela Sondej, and Jakub Zaremba for establishing the study plots and for logistical help during field data collection. We also thank the two anonymous reviewers for the comments and constructive feedbacks.

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The authors declared that they have no conflict of interest.

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Authors and Affiliations

  1. Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, 1958, Frederiksberg C, Denmark

    Seid Muhie Dawud, Karsten Raulund-Rasmussen & Lars Vesterdal

  2. Natural Resources Institute Finland (Luke), P.O. Box 68, 80101, Joensuu, Finland

    Timo Domisch & Leena Finér

  3. Faculty of Biology, University of Warsaw, Białowieża Geobotanical Station, Sportowa 19, 17-230, Białowieża, Poland

    Bogdan Jaroszewicz

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  1. Seid Muhie Dawud
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Correspondence to Seid Muhie Dawud.

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L. Vesterdal, K. Raulund-Rasmussen, L. Finér and B. Jaroszewicz designed the research; S.M. Dawud, T. Domisch, L. Vesterdal and K. Raulund-Rasmussen performed the research; S.M. Dawud analyzed the data; S.M. Dawud and L. Vesterdal wrote the paper with contributions from K. Raulund-Rasmussen, T. Domisch, L. Finér and B. Jaroszewicz.

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Dawud, S.M., Raulund-Rasmussen, K., Domisch, T. et al. Is Tree Species Diversity or Species Identity the More Important Driver of Soil Carbon Stocks, C/N Ratio, and pH?. Ecosystems 19, 645–660 (2016). https://doi.org/10.1007/s10021-016-9958-1

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